/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.buffer;

import io.netty.util.ByteProcessor;
import io.netty.util.ReferenceCounted;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.channels.FileChannel;
import java.nio.channels.GatheringByteChannel;
import java.nio.channels.ScatteringByteChannel;
import java.nio.charset.Charset;
import java.nio.charset.UnsupportedCharsetException;

/**
 * A random and sequential accessible sequence of zero or more bytes (octets).
 * This interface provides an abstract view for one or more primitive byte
 * arrays ({@code byte[]}) and {@linkplain ByteBuffer NIO buffers}.
 *
 * <h3>Creation of a buffer</h3>
 *
 * It is recommended to create a new buffer using the helper methods in
 * {@link Unpooled} rather than calling an individual implementation's
 * constructor.
 *
 * <h3>Random Access Indexing</h3>
 *
 * Just like an ordinary primitive byte array, {@link ByteBuf} uses
 * <a href="http://en.wikipedia.org/wiki/Zero-based_numbering">zero-based
 * indexing</a>. It means the index of the first byte is always {@code 0} and
 * the index of the last byte is always {@link #capacity() capacity - 1}. For
 * example, to iterate all bytes of a buffer, you can do the following,
 * regardless of its internal implementation:
 *
 * <pre>
 * {@link ByteBuf} buffer = ...;
 * for (int i = 0; i &lt; buffer.capacity(); i ++) {
 *     byte b = buffer.getByte(i);
 *     System.out.println((char) b);
 * }
 * </pre>
 *
 * <h3>Sequential Access Indexing</h3>
 *
 * {@link ByteBuf} provides two pointer variables to support sequential read and
 * write operations - {@link #readerIndex() readerIndex} for a read operation
 * and {@link #writerIndex() writerIndex} for a write operation respectively.
 * The following diagram shows how a buffer is segmented into three areas by the
 * two pointers:
 *
 * <pre>
 *      +-------------------+------------------+------------------+
 *      | discardable bytes |  readable bytes  |  writable bytes  |
 *      |                   |     (CONTENT)    |                  |
 *      +-------------------+------------------+------------------+
 *      |                   |                  |                  |
 *      0      <=      readerIndex   <=   writerIndex    <=    capacity
 * </pre>
 *
 * <h4>Readable bytes (the actual content)</h4>
 *
 * This segment is where the actual data is stored. Any operation whose name
 * starts with {@code read} or {@code skip} will get or skip the data at the
 * current {@link #readerIndex() readerIndex} and increase it by the number of
 * read bytes. If the argument of the read operation is also a {@link ByteBuf}
 * and no destination index is specified, the specified buffer's
 * {@link #writerIndex() writerIndex} is increased together.
 * <p>
 * If there's not enough content left, {@link IndexOutOfBoundsException} is
 * raised. The default value of newly allocated, wrapped or copied buffer's
 * {@link #readerIndex() readerIndex} is {@code 0}.
 *
 * <pre>
 * // Iterates the readable bytes of a buffer.
 * {@link ByteBuf} buffer = ...;
 * while (buffer.isReadable()) {
 *     System.out.println(buffer.readByte());
 * }
 * </pre>
 *
 * <h4>Writable bytes</h4>
 *
 * This segment is a undefined space which needs to be filled. Any operation
 * whose name starts with {@code write} will write the data at the current
 * {@link #writerIndex() writerIndex} and increase it by the number of written
 * bytes. If the argument of the write operation is also a {@link ByteBuf}, and
 * no source index is specified, the specified buffer's {@link #readerIndex()
 * readerIndex} is increased together.
 * <p>
 * If there's not enough writable bytes left, {@link IndexOutOfBoundsException}
 * is raised. The default value of newly allocated buffer's
 * {@link #writerIndex() writerIndex} is {@code 0}. The default value of wrapped
 * or copied buffer's {@link #writerIndex() writerIndex} is the
 * {@link #capacity() capacity} of the buffer.
 *
 * <pre>
 * // Fills the writable bytes of a buffer with random integers.
 * {@link ByteBuf} buffer = ...;
 * while (buffer.maxWritableBytes() >= 4) {
 *     buffer.writeInt(random.nextInt());
 * }
 * </pre>
 *
 * <h4>Discardable bytes</h4>
 *
 * This segment contains the bytes which were read already by a read operation.
 * Initially, the size of this segment is {@code 0}, but its size increases up
 * to the {@link #writerIndex() writerIndex} as read operations are executed.
 * The read bytes can be discarded by calling {@link #discardReadBytes()} to
 * reclaim unused area as depicted by the following diagram:
 *
 * <pre>
 *  BEFORE discardReadBytes()
 *
 *      +-------------------+------------------+------------------+
 *      | discardable bytes |  readable bytes  |  writable bytes  |
 *      +-------------------+------------------+------------------+
 *      |                   |                  |                  |
 *      0      <=      readerIndex   <=   writerIndex    <=    capacity
 *
 *
 *  AFTER discardReadBytes()
 *
 *      +------------------+--------------------------------------+
 *      |  readable bytes  |    writable bytes (got more space)   |
 *      +------------------+--------------------------------------+
 *      |                  |                                      |
 * readerIndex (0) <= writerIndex (decreased)        <=        capacity
 * </pre>
 *
 * Please note that there is no guarantee about the content of writable bytes
 * after calling {@link #discardReadBytes()}. The writable bytes will not be
 * moved in most cases and could even be filled with completely different data
 * depending on the underlying buffer implementation.
 *
 * <h4>Clearing the buffer indexes</h4>
 *
 * You can set both {@link #readerIndex() readerIndex} and {@link #writerIndex()
 * writerIndex} to {@code 0} by calling {@link #clear()}. It does not clear the
 * buffer content (e.g. filling with {@code 0}) but just clears the two
 * pointers. Please also note that the semantic of this operation is different
 * from {@link ByteBuffer#clear()}.
 *
 * <pre>
 *  BEFORE clear()
 *
 *      +-------------------+------------------+------------------+
 *      | discardable bytes |  readable bytes  |  writable bytes  |
 *      +-------------------+------------------+------------------+
 *      |                   |                  |                  |
 *      0      <=      readerIndex   <=   writerIndex    <=    capacity
 *
 *
 *  AFTER clear()
 *
 *      +---------------------------------------------------------+
 *      |             writable bytes (got more space)             |
 *      +---------------------------------------------------------+
 *      |                                                         |
 *      0 = readerIndex = writerIndex            <=            capacity
 * </pre>
 *
 * <h3>Search operations</h3>
 *
 * For simple single-byte searches, use {@link #indexOf(int, int, byte)} and
 * {@link #bytesBefore(int, int, byte)}. {@link #bytesBefore(byte)} is
 * especially useful when you deal with a {@code NUL}-terminated string. For
 * complicated searches, use {@link #forEachByte(int, int, ByteProcessor)} with
 * a {@link ByteProcessor} implementation.
 *
 * <h3>Mark and reset</h3>
 *
 * There are two marker indexes in every buffer. One is for storing
 * {@link #readerIndex() readerIndex} and the other is for storing
 * {@link #writerIndex() writerIndex}. You can always reposition one of the two
 * indexes by calling a reset method. It works in a similar fashion to the mark
 * and reset methods in {@link InputStream} except that there's no
 * {@code readlimit}.
 *
 * <h3>Derived buffers</h3>
 *
 * You can create a view of an existing buffer by calling one of the following
 * methods:
 * <ul>
 * <li>{@link #duplicate()}</li>
 * <li>{@link #slice()}</li>
 * <li>{@link #slice(int, int)}</li>
 * <li>{@link #readSlice(int)}</li>
 * <li>{@link #retainedDuplicate()}</li>
 * <li>{@link #retainedSlice()}</li>
 * <li>{@link #retainedSlice(int, int)}</li>
 * <li>{@link #readRetainedSlice(int)}</li>
 * </ul>
 * A derived buffer will have an independent {@link #readerIndex() readerIndex},
 * {@link #writerIndex() writerIndex} and marker indexes, while it shares other
 * internal data representation, just like a NIO buffer does.
 * <p>
 * In case a completely fresh copy of an existing buffer is required, please
 * call {@link #copy()} method instead.
 *
 * <h4>Non-retained and retained derived buffers</h4>
 *
 * Note that the {@link #duplicate()}, {@link #slice()},
 * {@link #slice(int, int)} and {@link #readSlice(int)} does NOT call
 * {@link #retain()} on the returned derived buffer, and thus its reference
 * count will NOT be increased. If you need to create a derived buffer with
 * increased reference count, consider using {@link #retainedDuplicate()},
 * {@link #retainedSlice()}, {@link #retainedSlice(int, int)} and
 * {@link #readRetainedSlice(int)} which may return a buffer implementation that
 * produces less garbage.
 *
 * <h3>Conversion to existing JDK types</h3>
 *
 * <h4>Byte array</h4>
 *
 * If a {@link ByteBuf} is backed by a byte array (i.e. {@code byte[]}), you can
 * access it directly via the {@link #array()} method. To determine if a buffer
 * is backed by a byte array, {@link #hasArray()} should be used.
 *
 * <h4>NIO Buffers</h4>
 *
 * If a {@link ByteBuf} can be converted into an NIO {@link ByteBuffer} which
 * shares its content (i.e. view buffer), you can get it via the
 * {@link #nioBuffer()} method. To determine if a buffer can be converted into
 * an NIO buffer, use {@link #nioBufferCount()}.
 *
 * <h4>Strings</h4>
 *
 * Various {@link #toString(Charset)} methods convert a {@link ByteBuf} into a
 * {@link String}. Please note that {@link #toString()} is not a conversion
 * method.
 *
 * <h4>I/O Streams</h4>
 *
 * Please refer to {@link ByteBufInputStream} and {@link ByteBufOutputStream}.
 */
@SuppressWarnings("ClassMayBeInterface")
public abstract class ByteBuf implements ReferenceCounted, Comparable<ByteBuf>
{

    /**
     * Returns the number of bytes (octets) this buffer can contain.
     */
    public abstract int capacity();

    /**
     * Adjusts the capacity of this buffer. If the {@code newCapacity} is less
     * than the current capacity, the content of this buffer is truncated. If
     * the {@code newCapacity} is greater than the current capacity, the buffer
     * is appended with unspecified data whose length is
     * {@code (newCapacity - currentCapacity)}.
     */
    public abstract ByteBuf capacity(int newCapacity);

    /**
     * Returns the maximum allowed capacity of this buffer. If a user attempts
     * to increase the capacity of this buffer beyond the maximum capacity using
     * {@link #capacity(int)} or {@link #ensureWritable(int)}, those methods
     * will raise an {@link IllegalArgumentException}.
     */
    public abstract int maxCapacity();

    /**
     * Returns the {@link ByteBufAllocator} which created this buffer.
     */
    public abstract ByteBufAllocator alloc();

    /**
     * Returns the
     * <a href="http://en.wikipedia.org/wiki/Endianness">endianness</a> of this
     * buffer.
     *
     * @deprecated use the Little Endian accessors, e.g. {@code getShortLE},
     *             {@code getIntLE} instead of creating a buffer with swapped
     *             {@code endianness}.
     */
    @Deprecated
    public abstract ByteOrder order();

    /**
     * Returns a buffer with the specified {@code endianness} which shares the
     * whole region, indexes, and marks of this buffer. Modifying the content,
     * the indexes, or the marks of the returned buffer or this buffer affects
     * each other's content, indexes, and marks. If the specified
     * {@code endianness} is identical to this buffer's byte order, this method
     * can return {@code this}. This method does not modify {@code readerIndex}
     * or {@code writerIndex} of this buffer.
     *
     * @deprecated use the Little Endian accessors, e.g. {@code getShortLE},
     *             {@code getIntLE} instead of creating a buffer with swapped
     *             {@code endianness}.
     */
    @Deprecated
    public abstract ByteBuf order(ByteOrder endianness);

    /**
     * Return the underlying buffer instance if this buffer is a wrapper of
     * another buffer.
     *
     * @return {@code null} if this buffer is not a wrapper
     */
    public abstract ByteBuf unwrap();

    /**
     * Returns {@code true} if and only if this buffer is backed by an NIO
     * direct buffer.
     */
    public abstract boolean isDirect();

    /**
     * Returns {@code true} if and only if this buffer is read-only.
     */
    public abstract boolean isReadOnly();

    /**
     * Returns a read-only version of this buffer.
     */
    public abstract ByteBuf asReadOnly();

    /**
     * Returns the {@code readerIndex} of this buffer.
     */
    public abstract int readerIndex();

    /**
     * Sets the {@code readerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code readerIndex} is
     *         less than {@code 0} or greater than {@code this.writerIndex}
     */
    public abstract ByteBuf readerIndex(int readerIndex);

    /**
     * Returns the {@code writerIndex} of this buffer.
     */
    public abstract int writerIndex();

    /**
     * Sets the {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code writerIndex} is
     *         less than {@code this.readerIndex} or greater than
     *         {@code this.capacity}
     */
    public abstract ByteBuf writerIndex(int writerIndex);

    /**
     * Sets the {@code readerIndex} and {@code writerIndex} of this buffer in
     * one shot. This method is useful when you have to worry about the
     * invocation order of {@link #readerIndex(int)} and
     * {@link #writerIndex(int)} methods. For example, the following code will
     * fail:
     *
     * <pre>
     * // Create a buffer whose readerIndex, writerIndex and capacity are
     * // 0, 0 and 8 respectively.
     * {@link ByteBuf} buf = {@link Unpooled}.buffer(8);
     *
     * // IndexOutOfBoundsException is thrown because the specified
     * // readerIndex (2) cannot be greater than the current writerIndex (0).
     * buf.readerIndex(2);
     * buf.writerIndex(4);
     * </pre>
     *
     * The following code will also fail:
     *
     * <pre>
     * // Create a buffer whose readerIndex, writerIndex and capacity are
     * // 0, 8 and 8 respectively.
     * {@link ByteBuf} buf = {@link Unpooled}.wrappedBuffer(new byte[8]);
     *
     * // readerIndex becomes 8.
     * buf.readLong();
     *
     * // IndexOutOfBoundsException is thrown because the specified
     * // writerIndex (4) cannot be less than the current readerIndex (8).
     * buf.writerIndex(4);
     * buf.readerIndex(2);
     * </pre>
     *
     * By contrast, this method guarantees that it never throws an
     * {@link IndexOutOfBoundsException} as long as the specified indexes meet
     * basic constraints, regardless what the current index values of the buffer
     * are:
     *
     * <pre>
     * // No matter what the current state of the buffer is, the following
     * // call always succeeds as long as the capacity of the buffer is not
     * // less than 4.
     * buf.setIndex(2, 4);
     * </pre>
     *
     * @throws IndexOutOfBoundsException if the specified {@code readerIndex} is
     *         less than 0, if the specified {@code writerIndex} is less than
     *         the specified {@code readerIndex} or if the specified
     *         {@code writerIndex} is greater than {@code this.capacity}
     */
    public abstract ByteBuf setIndex(int readerIndex, int writerIndex);

    /**
     * Returns the number of readable bytes which is equal to
     * {@code (this.writerIndex - this.readerIndex)}.
     */
    public abstract int readableBytes();

    /**
     * Returns the number of writable bytes which is equal to
     * {@code (this.capacity - this.writerIndex)}.
     */
    public abstract int writableBytes();

    /**
     * Returns the maximum possible number of writable bytes, which is equal to
     * {@code (this.maxCapacity - this.writerIndex)}.
     */
    public abstract int maxWritableBytes();

    /**
     * Returns {@code true} if and only if
     * {@code (this.writerIndex - this.readerIndex)} is greater than {@code 0}.
     */
    public abstract boolean isReadable();

    /**
     * Returns {@code true} if and only if this buffer contains equal to or more
     * than the specified number of elements.
     */
    public abstract boolean isReadable(int size);

    /**
     * Returns {@code true} if and only if
     * {@code (this.capacity - this.writerIndex)} is greater than {@code 0}.
     */
    public abstract boolean isWritable();

    /**
     * Returns {@code true} if and only if this buffer has enough room to allow
     * writing the specified number of elements.
     */
    public abstract boolean isWritable(int size);

    /**
     * Sets the {@code readerIndex} and {@code writerIndex} of this buffer to
     * {@code 0}. This method is identical to {@link #setIndex(int, int)
     * setIndex(0, 0)}.
     * <p>
     * Please note that the behavior of this method is different from that of
     * NIO buffer, which sets the {@code limit} to the {@code capacity} of the
     * buffer.
     */
    public abstract ByteBuf clear();

    /**
     * Marks the current {@code readerIndex} in this buffer. You can reposition
     * the current {@code readerIndex} to the marked {@code readerIndex} by
     * calling {@link #resetReaderIndex()}. The initial value of the marked
     * {@code readerIndex} is {@code 0}.
     */
    public abstract ByteBuf markReaderIndex();

    /**
     * Repositions the current {@code readerIndex} to the marked
     * {@code readerIndex} in this buffer.
     *
     * @throws IndexOutOfBoundsException if the current {@code writerIndex} is
     *         less than the marked {@code readerIndex}
     */
    public abstract ByteBuf resetReaderIndex();

    /**
     * Marks the current {@code writerIndex} in this buffer. You can reposition
     * the current {@code writerIndex} to the marked {@code writerIndex} by
     * calling {@link #resetWriterIndex()}. The initial value of the marked
     * {@code writerIndex} is {@code 0}.
     */
    public abstract ByteBuf markWriterIndex();

    /**
     * Repositions the current {@code writerIndex} to the marked
     * {@code writerIndex} in this buffer.
     *
     * @throws IndexOutOfBoundsException if the current {@code readerIndex} is
     *         greater than the marked {@code writerIndex}
     */
    public abstract ByteBuf resetWriterIndex();

    /**
     * Discards the bytes between the 0th index and {@code readerIndex}. It
     * moves the bytes between {@code readerIndex} and {@code writerIndex} to
     * the 0th index, and sets {@code readerIndex} and {@code writerIndex} to
     * {@code 0} and {@code oldWriterIndex - oldReaderIndex} respectively.
     * <p>
     * Please refer to the class documentation for more detailed explanation.
     */
    public abstract ByteBuf discardReadBytes();

    /**
     * Similar to {@link ByteBuf#discardReadBytes()} except that this method
     * might discard some, all, or none of read bytes depending on its internal
     * implementation to reduce overall memory bandwidth consumption at the cost
     * of potentially additional memory consumption.
     */
    public abstract ByteBuf discardSomeReadBytes();

    /**
     * Makes sure the number of {@linkplain #writableBytes() the writable bytes}
     * is equal to or greater than the specified value. If there is enough
     * writable bytes in this buffer, this method returns with no side effect.
     * Otherwise, it raises an {@link IllegalArgumentException}.
     *
     * @param minWritableBytes the expected minimum number of writable bytes
     * @throws IndexOutOfBoundsException if {@link #writerIndex()} +
     *         {@code minWritableBytes} &gt; {@link #maxCapacity()}
     */
    public abstract ByteBuf ensureWritable(int minWritableBytes);

    /**
     * Tries to make sure the number of {@linkplain #writableBytes() the
     * writable bytes} is equal to or greater than the specified value. Unlike
     * {@link #ensureWritable(int)}, this method does not raise an exception but
     * returns a code.
     *
     * @param minWritableBytes the expected minimum number of writable bytes
     * @param force When {@link #writerIndex()} + {@code minWritableBytes} &gt;
     *        {@link #maxCapacity()}:
     *        <ul>
     *        <li>{@code true} - the capacity of the buffer is expanded to
     *        {@link #maxCapacity()}</li>
     *        <li>{@code false} - the capacity of the buffer is unchanged</li>
     *        </ul>
     * @return {@code 0} if the buffer has enough writable bytes, and its
     *         capacity is unchanged. {@code 1} if the buffer does not have
     *         enough bytes, and its capacity is unchanged. {@code 2} if the
     *         buffer has enough writable bytes, and its capacity has been
     *         increased. {@code 3} if the buffer does not have enough bytes,
     *         but its capacity has been increased to its maximum.
     */
    public abstract int ensureWritable(int minWritableBytes, boolean force);

    /**
     * Gets a boolean at the specified absolute (@code index) in this buffer.
     * This method does not modify the {@code readerIndex} or
     * {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 1} is greater than
     *         {@code this.capacity}
     */
    public abstract boolean getBoolean(int index);

    /**
     * Gets a byte at the specified absolute {@code index} in this buffer. This
     * method does not modify {@code readerIndex} or {@code writerIndex} of this
     * buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 1} is greater than
     *         {@code this.capacity}
     */
    public abstract byte getByte(int index);

    /**
     * Gets an unsigned byte at the specified absolute {@code index} in this
     * buffer. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 1} is greater than
     *         {@code this.capacity}
     */
    public abstract short getUnsignedByte(int index);

    /**
     * Gets a 16-bit short integer at the specified absolute {@code index} in
     * this buffer. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 2} is greater than
     *         {@code this.capacity}
     */
    public abstract short getShort(int index);

    /**
     * Gets a 16-bit short integer at the specified absolute {@code index} in
     * this buffer in Little Endian Byte Order. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 2} is greater than
     *         {@code this.capacity}
     */
    public abstract short getShortLE(int index);

    /**
     * Gets an unsigned 16-bit short integer at the specified absolute
     * {@code index} in this buffer. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 2} is greater than
     *         {@code this.capacity}
     */
    public abstract int getUnsignedShort(int index);

    /**
     * Gets an unsigned 16-bit short integer at the specified absolute
     * {@code index} in this buffer in Little Endian Byte Order. This method
     * does not modify {@code readerIndex} or {@code writerIndex} of this
     * buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 2} is greater than
     *         {@code this.capacity}
     */
    public abstract int getUnsignedShortLE(int index);

    /**
     * Gets a 24-bit medium integer at the specified absolute {@code index} in
     * this buffer. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 3} is greater than
     *         {@code this.capacity}
     */
    public abstract int getMedium(int index);

    /**
     * Gets a 24-bit medium integer at the specified absolute {@code index} in
     * this buffer in the Little Endian Byte Order. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 3} is greater than
     *         {@code this.capacity}
     */
    public abstract int getMediumLE(int index);

    /**
     * Gets an unsigned 24-bit medium integer at the specified absolute
     * {@code index} in this buffer. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 3} is greater than
     *         {@code this.capacity}
     */
    public abstract int getUnsignedMedium(int index);

    /**
     * Gets an unsigned 24-bit medium integer at the specified absolute
     * {@code index} in this buffer in Little Endian Byte Order. This method
     * does not modify {@code readerIndex} or {@code writerIndex} of this
     * buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 3} is greater than
     *         {@code this.capacity}
     */
    public abstract int getUnsignedMediumLE(int index);

    /**
     * Gets a 32-bit integer at the specified absolute {@code index} in this
     * buffer. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 4} is greater than
     *         {@code this.capacity}
     */
    public abstract int getInt(int index);

    /**
     * Gets a 32-bit integer at the specified absolute {@code index} in this
     * buffer with Little Endian Byte Order. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 4} is greater than
     *         {@code this.capacity}
     */
    public abstract int getIntLE(int index);

    /**
     * Gets an unsigned 32-bit integer at the specified absolute {@code index}
     * in this buffer. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 4} is greater than
     *         {@code this.capacity}
     */
    public abstract long getUnsignedInt(int index);

    /**
     * Gets an unsigned 32-bit integer at the specified absolute {@code index}
     * in this buffer in Little Endian Byte Order. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 4} is greater than
     *         {@code this.capacity}
     */
    public abstract long getUnsignedIntLE(int index);

    /**
     * Gets a 64-bit long integer at the specified absolute {@code index} in
     * this buffer. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 8} is greater than
     *         {@code this.capacity}
     */
    public abstract long getLong(int index);

    /**
     * Gets a 64-bit long integer at the specified absolute {@code index} in
     * this buffer in Little Endian Byte Order. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 8} is greater than
     *         {@code this.capacity}
     */
    public abstract long getLongLE(int index);

    /**
     * Gets a 2-byte UTF-16 character at the specified absolute {@code index} in
     * this buffer. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 2} is greater than
     *         {@code this.capacity}
     */
    public abstract char getChar(int index);

    /**
     * Gets a 32-bit floating point number at the specified absolute
     * {@code index} in this buffer. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 4} is greater than
     *         {@code this.capacity}
     */
    public abstract float getFloat(int index);

    /**
     * Gets a 64-bit floating point number at the specified absolute
     * {@code index} in this buffer. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 8} is greater than
     *         {@code this.capacity}
     */
    public abstract double getDouble(int index);

    /**
     * Transfers this buffer's data to the specified destination starting at the
     * specified absolute {@code index} until the destination becomes
     * non-writable. This method is basically same with
     * {@link #getBytes(int, ByteBuf, int, int)}, except that this method
     * increases the {@code writerIndex} of the destination by the number of the
     * transferred bytes while {@link #getBytes(int, ByteBuf, int, int)} does
     * not. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of the source buffer (i.e. {@code this}).
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or if {@code index + dst.writableBytes} is greater
     *         than {@code this.capacity}
     */
    public abstract ByteBuf getBytes(int index, ByteBuf dst);

    /**
     * Transfers this buffer's data to the specified destination starting at the
     * specified absolute {@code index}. This method is basically same with
     * {@link #getBytes(int, ByteBuf, int, int)}, except that this method
     * increases the {@code writerIndex} of the destination by the number of the
     * transferred bytes while {@link #getBytes(int, ByteBuf, int, int)} does
     * not. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of the source buffer (i.e. {@code this}).
     *
     * @param length the number of bytes to transfer
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0}, if {@code index + length} is greater than
     *         {@code this.capacity}, or if {@code length} is greater than
     *         {@code dst.writableBytes}
     */
    public abstract ByteBuf getBytes(int index, ByteBuf dst, int length);

    /**
     * Transfers this buffer's data to the specified destination starting at the
     * specified absolute {@code index}. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of both the source (i.e.
     * {@code this}) and the destination.
     *
     * @param dstIndex the first index of the destination
     * @param length the number of bytes to transfer
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0}, if the specified {@code dstIndex} is less than
     *         {@code 0}, if {@code index + length} is greater than
     *         {@code this.capacity}, or if {@code dstIndex + length} is greater
     *         than {@code dst.capacity}
     */
    public abstract ByteBuf getBytes(int index, ByteBuf dst, int dstIndex,
            int length);

    /**
     * Transfers this buffer's data to the specified destination starting at the
     * specified absolute {@code index}. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or if {@code index + dst.length} is greater than
     *         {@code this.capacity}
     */
    public abstract ByteBuf getBytes(int index, byte[] dst);

    /**
     * Transfers this buffer's data to the specified destination starting at the
     * specified absolute {@code index}. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @param dstIndex the first index of the destination
     * @param length the number of bytes to transfer
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0}, if the specified {@code dstIndex} is less than
     *         {@code 0}, if {@code index + length} is greater than
     *         {@code this.capacity}, or if {@code dstIndex + length} is greater
     *         than {@code dst.length}
     */
    public abstract ByteBuf getBytes(int index, byte[] dst, int dstIndex,
            int length);

    /**
     * Transfers this buffer's data to the specified destination starting at the
     * specified absolute {@code index} until the destination's position reaches
     * its limit. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of this buffer while the destination's
     * {@code position} will be increased.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or if {@code index + dst.remaining()} is greater
     *         than {@code this.capacity}
     */
    public abstract ByteBuf getBytes(int index, ByteBuffer dst);

    /**
     * Transfers this buffer's data to the specified stream starting at the
     * specified absolute {@code index}. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @param length the number of bytes to transfer
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or if {@code index + length} is greater than
     *         {@code this.capacity}
     * @throws IOException if the specified stream threw an exception during I/O
     */
    public abstract ByteBuf getBytes(int index, OutputStream out, int length)
            throws IOException;

    /**
     * Transfers this buffer's data to the specified channel starting at the
     * specified absolute {@code index}. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @param length the maximum number of bytes to transfer
     *
     * @return the actual number of bytes written out to the specified channel
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or if {@code index + length} is greater than
     *         {@code this.capacity}
     * @throws IOException if the specified channel threw an exception during
     *         I/O
     */
    public abstract int getBytes(int index, GatheringByteChannel out,
            int length) throws IOException;

    /**
     * Transfers this buffer's data starting at the specified absolute
     * {@code index} to the specified channel starting at the given file
     * position. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of this buffer. This method does not modify the
     * channel's position.
     *
     * @param position the file position at which the transfer is to begin
     * @param length the maximum number of bytes to transfer
     *
     * @return the actual number of bytes written out to the specified channel
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or if {@code index + length} is greater than
     *         {@code this.capacity}
     * @throws IOException if the specified channel threw an exception during
     *         I/O
     */
    public abstract int getBytes(int index, FileChannel out, long position,
            int length) throws IOException;

    /**
     * Gets a {@link CharSequence} with the given length at the given index.
     *
     * @param length the length to read
     * @param charset that should be used
     * @return the sequence
     * @throws IndexOutOfBoundsException if {@code length} is greater than
     *         {@code this.readableBytes}
     */
    public abstract CharSequence getCharSequence(int index, int length,
            Charset charset);

    /**
     * Sets the specified boolean at the specified absolute {@code index} in
     * this buffer. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 1} is greater than
     *         {@code this.capacity}
     */
    public abstract ByteBuf setBoolean(int index, boolean value);

    /**
     * Sets the specified byte at the specified absolute {@code index} in this
     * buffer. The 24 high-order bits of the specified value are ignored. This
     * method does not modify {@code readerIndex} or {@code writerIndex} of this
     * buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 1} is greater than
     *         {@code this.capacity}
     */
    public abstract ByteBuf setByte(int index, int value);

    /**
     * Sets the specified 16-bit short integer at the specified absolute
     * {@code index} in this buffer. The 16 high-order bits of the specified
     * value are ignored. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 2} is greater than
     *         {@code this.capacity}
     */
    public abstract ByteBuf setShort(int index, int value);

    /**
     * Sets the specified 16-bit short integer at the specified absolute
     * {@code index} in this buffer with the Little Endian Byte Order. The 16
     * high-order bits of the specified value are ignored. This method does not
     * modify {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 2} is greater than
     *         {@code this.capacity}
     */
    public abstract ByteBuf setShortLE(int index, int value);

    /**
     * Sets the specified 24-bit medium integer at the specified absolute
     * {@code index} in this buffer. Please note that the most significant byte
     * is ignored in the specified value. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 3} is greater than
     *         {@code this.capacity}
     */
    public abstract ByteBuf setMedium(int index, int value);

    /**
     * Sets the specified 24-bit medium integer at the specified absolute
     * {@code index} in this buffer in the Little Endian Byte Order. Please note
     * that the most significant byte is ignored in the specified value. This
     * method does not modify {@code readerIndex} or {@code writerIndex} of this
     * buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 3} is greater than
     *         {@code this.capacity}
     */
    public abstract ByteBuf setMediumLE(int index, int value);

    /**
     * Sets the specified 32-bit integer at the specified absolute {@code index}
     * in this buffer. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 4} is greater than
     *         {@code this.capacity}
     */
    public abstract ByteBuf setInt(int index, int value);

    /**
     * Sets the specified 32-bit integer at the specified absolute {@code index}
     * in this buffer with Little Endian byte order . This method does not
     * modify {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 4} is greater than
     *         {@code this.capacity}
     */
    public abstract ByteBuf setIntLE(int index, int value);

    /**
     * Sets the specified 64-bit long integer at the specified absolute
     * {@code index} in this buffer. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 8} is greater than
     *         {@code this.capacity}
     */
    public abstract ByteBuf setLong(int index, long value);

    /**
     * Sets the specified 64-bit long integer at the specified absolute
     * {@code index} in this buffer in Little Endian Byte Order. This method
     * does not modify {@code readerIndex} or {@code writerIndex} of this
     * buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 8} is greater than
     *         {@code this.capacity}
     */
    public abstract ByteBuf setLongLE(int index, long value);

    /**
     * Sets the specified 2-byte UTF-16 character at the specified absolute
     * {@code index} in this buffer. The 16 high-order bits of the specified
     * value are ignored. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 2} is greater than
     *         {@code this.capacity}
     */
    public abstract ByteBuf setChar(int index, int value);

    /**
     * Sets the specified 32-bit floating-point number at the specified absolute
     * {@code index} in this buffer. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 4} is greater than
     *         {@code this.capacity}
     */
    public abstract ByteBuf setFloat(int index, float value);

    /**
     * Sets the specified 64-bit floating-point number at the specified absolute
     * {@code index} in this buffer. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or {@code index + 8} is greater than
     *         {@code this.capacity}
     */
    public abstract ByteBuf setDouble(int index, double value);

    /**
     * Transfers the specified source buffer's data to this buffer starting at
     * the specified absolute {@code index} until the source buffer becomes
     * unreadable. This method is basically same with
     * {@link #setBytes(int, ByteBuf, int, int)}, except that this method
     * increases the {@code readerIndex} of the source buffer by the number of
     * the transferred bytes while {@link #setBytes(int, ByteBuf, int, int)}
     * does not. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of the source buffer (i.e. {@code this}).
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or if {@code index + src.readableBytes} is greater
     *         than {@code this.capacity}
     */
    public abstract ByteBuf setBytes(int index, ByteBuf src);

    /**
     * Transfers the specified source buffer's data to this buffer starting at
     * the specified absolute {@code index}. This method is basically same with
     * {@link #setBytes(int, ByteBuf, int, int)}, except that this method
     * increases the {@code readerIndex} of the source buffer by the number of
     * the transferred bytes while {@link #setBytes(int, ByteBuf, int, int)}
     * does not. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of the source buffer (i.e. {@code this}).
     *
     * @param length the number of bytes to transfer
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0}, if {@code index + length} is greater than
     *         {@code this.capacity}, or if {@code length} is greater than
     *         {@code src.readableBytes}
     */
    public abstract ByteBuf setBytes(int index, ByteBuf src, int length);

    /**
     * Transfers the specified source buffer's data to this buffer starting at
     * the specified absolute {@code index}. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of both the source (i.e.
     * {@code this}) and the destination.
     *
     * @param srcIndex the first index of the source
     * @param length the number of bytes to transfer
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0}, if the specified {@code srcIndex} is less than
     *         {@code 0}, if {@code index + length} is greater than
     *         {@code this.capacity}, or if {@code srcIndex + length} is greater
     *         than {@code src.capacity}
     */
    public abstract ByteBuf setBytes(int index, ByteBuf src, int srcIndex,
            int length);

    /**
     * Transfers the specified source array's data to this buffer starting at
     * the specified absolute {@code index}. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or if {@code index + src.length} is greater than
     *         {@code this.capacity}
     */
    public abstract ByteBuf setBytes(int index, byte[] src);

    /**
     * Transfers the specified source array's data to this buffer starting at
     * the specified absolute {@code index}. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0}, if the specified {@code srcIndex} is less than
     *         {@code 0}, if {@code index + length} is greater than
     *         {@code this.capacity}, or if {@code srcIndex + length} is greater
     *         than {@code src.length}
     */
    public abstract ByteBuf setBytes(int index, byte[] src, int srcIndex,
            int length);

    /**
     * Transfers the specified source buffer's data to this buffer starting at
     * the specified absolute {@code index} until the source buffer's position
     * reaches its limit. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of this buffer.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or if {@code index + src.remaining()} is greater
     *         than {@code this.capacity}
     */
    public abstract ByteBuf setBytes(int index, ByteBuffer src);

    /**
     * Transfers the content of the specified source stream to this buffer
     * starting at the specified absolute {@code index}. This method does not
     * modify {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @param length the number of bytes to transfer
     *
     * @return the actual number of bytes read in from the specified channel.
     *         {@code -1} if the specified channel is closed.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or if {@code index + length} is greater than
     *         {@code this.capacity}
     * @throws IOException if the specified stream threw an exception during I/O
     */
    public abstract int setBytes(int index, InputStream in, int length)
            throws IOException;

    /**
     * Transfers the content of the specified source channel to this buffer
     * starting at the specified absolute {@code index}. This method does not
     * modify {@code readerIndex} or {@code writerIndex} of this buffer.
     *
     * @param length the maximum number of bytes to transfer
     *
     * @return the actual number of bytes read in from the specified channel.
     *         {@code -1} if the specified channel is closed.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or if {@code index + length} is greater than
     *         {@code this.capacity}
     * @throws IOException if the specified channel threw an exception during
     *         I/O
     */
    public abstract int setBytes(int index, ScatteringByteChannel in,
            int length) throws IOException;

    /**
     * Transfers the content of the specified source channel starting at the
     * given file position to this buffer starting at the specified absolute
     * {@code index}. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of this buffer. This method does not modify the
     * channel's position.
     *
     * @param position the file position at which the transfer is to begin
     * @param length the maximum number of bytes to transfer
     *
     * @return the actual number of bytes read in from the specified channel.
     *         {@code -1} if the specified channel is closed.
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or if {@code index + length} is greater than
     *         {@code this.capacity}
     * @throws IOException if the specified channel threw an exception during
     *         I/O
     */
    public abstract int setBytes(int index, FileChannel in, long position,
            int length) throws IOException;

    /**
     * Fills this buffer with <tt>NUL (0x00)</tt> starting at the specified
     * absolute {@code index}. This method does not modify {@code readerIndex}
     * or {@code writerIndex} of this buffer.
     *
     * @param length the number of <tt>NUL</tt>s to write to the buffer
     *
     * @throws IndexOutOfBoundsException if the specified {@code index} is less
     *         than {@code 0} or if {@code index + length} is greater than
     *         {@code this.capacity}
     */
    public abstract ByteBuf setZero(int index, int length);

    /**
     * Writes the specified {@link CharSequence} at the current
     * {@code writerIndex} and increases the {@code writerIndex} by the written
     * bytes.
     *
     * @param index on which the sequence should be written
     * @param sequence to write
     * @param charset that should be used.
     * @return the written number of bytes.
     * @throws IndexOutOfBoundsException if {@code this.writableBytes} is not
     *         large enough to write the whole sequence
     */
    public abstract int setCharSequence(int index, CharSequence sequence,
            Charset charset);

    /**
     * Gets a boolean at the current {@code readerIndex} and increases the
     * {@code readerIndex} by {@code 1} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 1}
     */
    public abstract boolean readBoolean();

    /**
     * Gets a byte at the current {@code readerIndex} and increases the
     * {@code readerIndex} by {@code 1} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 1}
     */
    public abstract byte readByte();

    /**
     * Gets an unsigned byte at the current {@code readerIndex} and increases
     * the {@code readerIndex} by {@code 1} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 1}
     */
    public abstract short readUnsignedByte();

    /**
     * Gets a 16-bit short integer at the current {@code readerIndex} and
     * increases the {@code readerIndex} by {@code 2} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 2}
     */
    public abstract short readShort();

    /**
     * Gets a 16-bit short integer at the current {@code readerIndex} in the
     * Little Endian Byte Order and increases the {@code readerIndex} by
     * {@code 2} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 2}
     */
    public abstract short readShortLE();

    /**
     * Gets an unsigned 16-bit short integer at the current {@code readerIndex}
     * and increases the {@code readerIndex} by {@code 2} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 2}
     */
    public abstract int readUnsignedShort();

    /**
     * Gets an unsigned 16-bit short integer at the current {@code readerIndex}
     * in the Little Endian Byte Order and increases the {@code readerIndex} by
     * {@code 2} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 2}
     */
    public abstract int readUnsignedShortLE();

    /**
     * Gets a 24-bit medium integer at the current {@code readerIndex} and
     * increases the {@code readerIndex} by {@code 3} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 3}
     */
    public abstract int readMedium();

    /**
     * Gets a 24-bit medium integer at the current {@code readerIndex} in the
     * Little Endian Byte Order and increases the {@code readerIndex} by
     * {@code 3} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 3}
     */
    public abstract int readMediumLE();

    /**
     * Gets an unsigned 24-bit medium integer at the current {@code readerIndex}
     * and increases the {@code readerIndex} by {@code 3} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 3}
     */
    public abstract int readUnsignedMedium();

    /**
     * Gets an unsigned 24-bit medium integer at the current {@code readerIndex}
     * in the Little Endian Byte Order and increases the {@code readerIndex} by
     * {@code 3} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 3}
     */
    public abstract int readUnsignedMediumLE();

    /**
     * Gets a 32-bit integer at the current {@code readerIndex} and increases
     * the {@code readerIndex} by {@code 4} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 4}
     */
    public abstract int readInt();

    /**
     * Gets a 32-bit integer at the current {@code readerIndex} in the Little
     * Endian Byte Order and increases the {@code readerIndex} by {@code 4} in
     * this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 4}
     */
    public abstract int readIntLE();

    /**
     * Gets an unsigned 32-bit integer at the current {@code readerIndex} and
     * increases the {@code readerIndex} by {@code 4} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 4}
     */
    public abstract long readUnsignedInt();

    /**
     * Gets an unsigned 32-bit integer at the current {@code readerIndex} in the
     * Little Endian Byte Order and increases the {@code readerIndex} by
     * {@code 4} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 4}
     */
    public abstract long readUnsignedIntLE();

    /**
     * Gets a 64-bit integer at the current {@code readerIndex} and increases
     * the {@code readerIndex} by {@code 8} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 8}
     */
    public abstract long readLong();

    /**
     * Gets a 64-bit integer at the current {@code readerIndex} in the Little
     * Endian Byte Order and increases the {@code readerIndex} by {@code 8} in
     * this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 8}
     */
    public abstract long readLongLE();

    /**
     * Gets a 2-byte UTF-16 character at the current {@code readerIndex} and
     * increases the {@code readerIndex} by {@code 2} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 2}
     */
    public abstract char readChar();

    /**
     * Gets a 32-bit floating point number at the current {@code readerIndex}
     * and increases the {@code readerIndex} by {@code 4} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 4}
     */
    public abstract float readFloat();

    /**
     * Gets a 64-bit floating point number at the current {@code readerIndex}
     * and increases the {@code readerIndex} by {@code 8} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.readableBytes} is less
     *         than {@code 8}
     */
    public abstract double readDouble();

    /**
     * Transfers this buffer's data to a newly created buffer starting at the
     * current {@code readerIndex} and increases the {@code readerIndex} by the
     * number of the transferred bytes (= {@code length}). The returned buffer's
     * {@code readerIndex} and {@code writerIndex} are {@code 0} and
     * {@code length} respectively.
     *
     * @param length the number of bytes to transfer
     *
     * @return the newly created buffer which contains the transferred bytes
     *
     * @throws IndexOutOfBoundsException if {@code length} is greater than
     *         {@code this.readableBytes}
     */
    public abstract ByteBuf readBytes(int length);

    /**
     * Returns a new slice of this buffer's sub-region starting at the current
     * {@code readerIndex} and increases the {@code readerIndex} by the size of
     * the new slice (= {@code length}).
     * <p>
     * Also be aware that this method will NOT call {@link #retain()} and so the
     * reference count will NOT be increased.
     *
     * @param length the size of the new slice
     *
     * @return the newly created slice
     *
     * @throws IndexOutOfBoundsException if {@code length} is greater than
     *         {@code this.readableBytes}
     */
    public abstract ByteBuf readSlice(int length);

    /**
     * Returns a new retained slice of this buffer's sub-region starting at the
     * current {@code readerIndex} and increases the {@code readerIndex} by the
     * size of the new slice (= {@code length}).
     * <p>
     * Note that this method returns a {@linkplain #retain() retained} buffer
     * unlike {@link #readSlice(int)}. This method behaves similarly to
     * {@code readSlice(...).retain()} except that this method may return a
     * buffer implementation that produces less garbage.
     *
     * @param length the size of the new slice
     *
     * @return the newly created slice
     *
     * @throws IndexOutOfBoundsException if {@code length} is greater than
     *         {@code this.readableBytes}
     */
    public abstract ByteBuf readRetainedSlice(int length);

    /**
     * Transfers this buffer's data to the specified destination starting at the
     * current {@code readerIndex} until the destination becomes non-writable,
     * and increases the {@code readerIndex} by the number of the transferred
     * bytes. This method is basically same with
     * {@link #readBytes(ByteBuf, int, int)}, except that this method increases
     * the {@code writerIndex} of the destination by the number of the
     * transferred bytes while {@link #readBytes(ByteBuf, int, int)} does not.
     *
     * @throws IndexOutOfBoundsException if {@code dst.writableBytes} is greater
     *         than {@code this.readableBytes}
     */
    public abstract ByteBuf readBytes(ByteBuf dst);

    /**
     * Transfers this buffer's data to the specified destination starting at the
     * current {@code readerIndex} and increases the {@code readerIndex} by the
     * number of the transferred bytes (= {@code length}). This method is
     * basically same with {@link #readBytes(ByteBuf, int, int)}, except that
     * this method increases the {@code writerIndex} of the destination by the
     * number of the transferred bytes (= {@code length}) while
     * {@link #readBytes(ByteBuf, int, int)} does not.
     *
     * @throws IndexOutOfBoundsException if {@code length} is greater than
     *         {@code this.readableBytes} or if {@code length} is greater than
     *         {@code dst.writableBytes}
     */
    public abstract ByteBuf readBytes(ByteBuf dst, int length);

    /**
     * Transfers this buffer's data to the specified destination starting at the
     * current {@code readerIndex} and increases the {@code readerIndex} by the
     * number of the transferred bytes (= {@code length}).
     *
     * @param dstIndex the first index of the destination
     * @param length the number of bytes to transfer
     *
     * @throws IndexOutOfBoundsException if the specified {@code dstIndex} is
     *         less than {@code 0}, if {@code length} is greater than
     *         {@code this.readableBytes}, or if {@code dstIndex + length} is
     *         greater than {@code dst.capacity}
     */
    public abstract ByteBuf readBytes(ByteBuf dst, int dstIndex, int length);

    /**
     * Transfers this buffer's data to the specified destination starting at the
     * current {@code readerIndex} and increases the {@code readerIndex} by the
     * number of the transferred bytes (= {@code dst.length}).
     *
     * @throws IndexOutOfBoundsException if {@code dst.length} is greater than
     *         {@code this.readableBytes}
     */
    public abstract ByteBuf readBytes(byte[] dst);

    /**
     * Transfers this buffer's data to the specified destination starting at the
     * current {@code readerIndex} and increases the {@code readerIndex} by the
     * number of the transferred bytes (= {@code length}).
     *
     * @param dstIndex the first index of the destination
     * @param length the number of bytes to transfer
     *
     * @throws IndexOutOfBoundsException if the specified {@code dstIndex} is
     *         less than {@code 0}, if {@code length} is greater than
     *         {@code this.readableBytes}, or if {@code dstIndex + length} is
     *         greater than {@code dst.length}
     */
    public abstract ByteBuf readBytes(byte[] dst, int dstIndex, int length);

    /**
     * Transfers this buffer's data to the specified destination starting at the
     * current {@code readerIndex} until the destination's position reaches its
     * limit, and increases the {@code readerIndex} by the number of the
     * transferred bytes.
     *
     * @throws IndexOutOfBoundsException if {@code dst.remaining()} is greater
     *         than {@code this.readableBytes}
     */
    public abstract ByteBuf readBytes(ByteBuffer dst);

    /**
     * Transfers this buffer's data to the specified stream starting at the
     * current {@code readerIndex}.
     *
     * @param length the number of bytes to transfer
     *
     * @throws IndexOutOfBoundsException if {@code length} is greater than
     *         {@code this.readableBytes}
     * @throws IOException if the specified stream threw an exception during I/O
     */
    public abstract ByteBuf readBytes(OutputStream out, int length)
            throws IOException;

    /**
     * Transfers this buffer's data to the specified stream starting at the
     * current {@code readerIndex}.
     *
     * @param length the maximum number of bytes to transfer
     *
     * @return the actual number of bytes written out to the specified channel
     *
     * @throws IndexOutOfBoundsException if {@code length} is greater than
     *         {@code this.readableBytes}
     * @throws IOException if the specified channel threw an exception during
     *         I/O
     */
    public abstract int readBytes(GatheringByteChannel out, int length)
            throws IOException;

    /**
     * Gets a {@link CharSequence} with the given length at the current
     * {@code readerIndex} and increases the {@code readerIndex} by the given
     * length.
     *
     * @param length the length to read
     * @param charset that should be used
     * @return the sequence
     * @throws IndexOutOfBoundsException if {@code length} is greater than
     *         {@code this.readableBytes}
     */
    public abstract CharSequence readCharSequence(int length, Charset charset);

    /**
     * Transfers this buffer's data starting at the current {@code readerIndex}
     * to the specified channel starting at the given file position. This method
     * does not modify the channel's position.
     *
     * @param position the file position at which the transfer is to begin
     * @param length the maximum number of bytes to transfer
     *
     * @return the actual number of bytes written out to the specified channel
     *
     * @throws IndexOutOfBoundsException if {@code length} is greater than
     *         {@code this.readableBytes}
     * @throws IOException if the specified channel threw an exception during
     *         I/O
     */
    public abstract int readBytes(FileChannel out, long position, int length)
            throws IOException;

    /**
     * Increases the current {@code readerIndex} by the specified {@code length}
     * in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code length} is greater than
     *         {@code this.readableBytes}
     */
    public abstract ByteBuf skipBytes(int length);

    /**
     * Sets the specified boolean at the current {@code writerIndex} and
     * increases the {@code writerIndex} by {@code 1} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.writableBytes} is less
     *         than {@code 1}
     */
    public abstract ByteBuf writeBoolean(boolean value);

    /**
     * Sets the specified byte at the current {@code writerIndex} and increases
     * the {@code writerIndex} by {@code 1} in this buffer. The 24 high-order
     * bits of the specified value are ignored.
     *
     * @throws IndexOutOfBoundsException if {@code this.writableBytes} is less
     *         than {@code 1}
     */
    public abstract ByteBuf writeByte(int value);

    /**
     * Sets the specified 16-bit short integer at the current
     * {@code writerIndex} and increases the {@code writerIndex} by {@code 2} in
     * this buffer. The 16 high-order bits of the specified value are ignored.
     *
     * @throws IndexOutOfBoundsException if {@code this.writableBytes} is less
     *         than {@code 2}
     */
    public abstract ByteBuf writeShort(int value);

    /**
     * Sets the specified 16-bit short integer in the Little Endian Byte Order
     * at the current {@code writerIndex} and increases the {@code writerIndex}
     * by {@code 2} in this buffer. The 16 high-order bits of the specified
     * value are ignored.
     *
     * @throws IndexOutOfBoundsException if {@code this.writableBytes} is less
     *         than {@code 2}
     */
    public abstract ByteBuf writeShortLE(int value);

    /**
     * Sets the specified 24-bit medium integer at the current
     * {@code writerIndex} and increases the {@code writerIndex} by {@code 3} in
     * this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.writableBytes} is less
     *         than {@code 3}
     */
    public abstract ByteBuf writeMedium(int value);

    /**
     * Sets the specified 24-bit medium integer at the current
     * {@code writerIndex} in the Little Endian Byte Order and increases the
     * {@code writerIndex} by {@code 3} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.writableBytes} is less
     *         than {@code 3}
     */
    public abstract ByteBuf writeMediumLE(int value);

    /**
     * Sets the specified 32-bit integer at the current {@code writerIndex} and
     * increases the {@code writerIndex} by {@code 4} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.writableBytes} is less
     *         than {@code 4}
     */
    public abstract ByteBuf writeInt(int value);

    /**
     * Sets the specified 32-bit integer at the current {@code writerIndex} in
     * the Little Endian Byte Order and increases the {@code writerIndex} by
     * {@code 4} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.writableBytes} is less
     *         than {@code 4}
     */
    public abstract ByteBuf writeIntLE(int value);

    /**
     * Sets the specified 64-bit long integer at the current {@code writerIndex}
     * and increases the {@code writerIndex} by {@code 8} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.writableBytes} is less
     *         than {@code 8}
     */
    public abstract ByteBuf writeLong(long value);

    /**
     * Sets the specified 64-bit long integer at the current {@code writerIndex}
     * in the Little Endian Byte Order and increases the {@code writerIndex} by
     * {@code 8} in this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.writableBytes} is less
     *         than {@code 8}
     */
    public abstract ByteBuf writeLongLE(long value);

    /**
     * Sets the specified 2-byte UTF-16 character at the current
     * {@code writerIndex} and increases the {@code writerIndex} by {@code 2} in
     * this buffer. The 16 high-order bits of the specified value are ignored.
     *
     * @throws IndexOutOfBoundsException if {@code this.writableBytes} is less
     *         than {@code 2}
     */
    public abstract ByteBuf writeChar(int value);

    /**
     * Sets the specified 32-bit floating point number at the current
     * {@code writerIndex} and increases the {@code writerIndex} by {@code 4} in
     * this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.writableBytes} is less
     *         than {@code 4}
     */
    public abstract ByteBuf writeFloat(float value);

    /**
     * Sets the specified 64-bit floating point number at the current
     * {@code writerIndex} and increases the {@code writerIndex} by {@code 8} in
     * this buffer.
     *
     * @throws IndexOutOfBoundsException if {@code this.writableBytes} is less
     *         than {@code 8}
     */
    public abstract ByteBuf writeDouble(double value);

    /**
     * Transfers the specified source buffer's data to this buffer starting at
     * the current {@code writerIndex} until the source buffer becomes
     * unreadable, and increases the {@code writerIndex} by the number of the
     * transferred bytes. This method is basically same with
     * {@link #writeBytes(ByteBuf, int, int)}, except that this method increases
     * the {@code readerIndex} of the source buffer by the number of the
     * transferred bytes while {@link #writeBytes(ByteBuf, int, int)} does not.
     *
     * @throws IndexOutOfBoundsException if {@code src.readableBytes} is greater
     *         than {@code this.writableBytes}
     */
    public abstract ByteBuf writeBytes(ByteBuf src);

    /**
     * Transfers the specified source buffer's data to this buffer starting at
     * the current {@code writerIndex} and increases the {@code writerIndex} by
     * the number of the transferred bytes (= {@code length}). This method is
     * basically same with {@link #writeBytes(ByteBuf, int, int)}, except that
     * this method increases the {@code readerIndex} of the source buffer by the
     * number of the transferred bytes (= {@code length}) while
     * {@link #writeBytes(ByteBuf, int, int)} does not.
     *
     * @param length the number of bytes to transfer
     *
     * @throws IndexOutOfBoundsException if {@code length} is greater than
     *         {@code this.writableBytes} or if {@code length} is greater then
     *         {@code src.readableBytes}
     */
    public abstract ByteBuf writeBytes(ByteBuf src, int length);

    /**
     * Transfers the specified source buffer's data to this buffer starting at
     * the current {@code writerIndex} and increases the {@code writerIndex} by
     * the number of the transferred bytes (= {@code length}).
     *
     * @param srcIndex the first index of the source
     * @param length the number of bytes to transfer
     *
     * @throws IndexOutOfBoundsException if the specified {@code srcIndex} is
     *         less than {@code 0}, if {@code srcIndex + length} is greater than
     *         {@code src.capacity}, or if {@code length} is greater than
     *         {@code this.writableBytes}
     */
    public abstract ByteBuf writeBytes(ByteBuf src, int srcIndex, int length);

    /**
     * Transfers the specified source array's data to this buffer starting at
     * the current {@code writerIndex} and increases the {@code writerIndex} by
     * the number of the transferred bytes (= {@code src.length}).
     *
     * @throws IndexOutOfBoundsException if {@code src.length} is greater than
     *         {@code this.writableBytes}
     */
    public abstract ByteBuf writeBytes(byte[] src);

    /**
     * Transfers the specified source array's data to this buffer starting at
     * the current {@code writerIndex} and increases the {@code writerIndex} by
     * the number of the transferred bytes (= {@code length}).
     *
     * @param srcIndex the first index of the source
     * @param length the number of bytes to transfer
     *
     * @throws IndexOutOfBoundsException if the specified {@code srcIndex} is
     *         less than {@code 0}, if {@code srcIndex + length} is greater than
     *         {@code src.length}, or if {@code length} is greater than
     *         {@code this.writableBytes}
     */
    public abstract ByteBuf writeBytes(byte[] src, int srcIndex, int length);

    /**
     * Transfers the specified source buffer's data to this buffer starting at
     * the current {@code writerIndex} until the source buffer's position
     * reaches its limit, and increases the {@code writerIndex} by the number of
     * the transferred bytes.
     *
     * @throws IndexOutOfBoundsException if {@code src.remaining()} is greater
     *         than {@code this.writableBytes}
     */
    public abstract ByteBuf writeBytes(ByteBuffer src);

    /**
     * Transfers the content of the specified stream to this buffer starting at
     * the current {@code writerIndex} and increases the {@code writerIndex} by
     * the number of the transferred bytes.
     *
     * @param length the number of bytes to transfer
     *
     * @return the actual number of bytes read in from the specified stream
     *
     * @throws IndexOutOfBoundsException if {@code length} is greater than
     *         {@code this.writableBytes}
     * @throws IOException if the specified stream threw an exception during I/O
     */
    public abstract int writeBytes(InputStream in, int length)
            throws IOException;

    /**
     * Transfers the content of the specified channel to this buffer starting at
     * the current {@code writerIndex} and increases the {@code writerIndex} by
     * the number of the transferred bytes.
     *
     * @param length the maximum number of bytes to transfer
     *
     * @return the actual number of bytes read in from the specified channel
     *
     * @throws IndexOutOfBoundsException if {@code length} is greater than
     *         {@code this.writableBytes}
     * @throws IOException if the specified channel threw an exception during
     *         I/O
     */
    public abstract int writeBytes(ScatteringByteChannel in, int length)
            throws IOException;

    /**
     * Transfers the content of the specified channel starting at the given file
     * position to this buffer starting at the current {@code writerIndex} and
     * increases the {@code writerIndex} by the number of the transferred bytes.
     * This method does not modify the channel's position.
     *
     * @param position the file position at which the transfer is to begin
     * @param length the maximum number of bytes to transfer
     *
     * @return the actual number of bytes read in from the specified channel
     *
     * @throws IndexOutOfBoundsException if {@code length} is greater than
     *         {@code this.writableBytes}
     * @throws IOException if the specified channel threw an exception during
     *         I/O
     */
    public abstract int writeBytes(FileChannel in, long position, int length)
            throws IOException;

    /**
     * Fills this buffer with <tt>NUL (0x00)</tt> starting at the current
     * {@code writerIndex} and increases the {@code writerIndex} by the
     * specified {@code length}.
     *
     * @param length the number of <tt>NUL</tt>s to write to the buffer
     *
     * @throws IndexOutOfBoundsException if {@code length} is greater than
     *         {@code this.writableBytes}
     */
    public abstract ByteBuf writeZero(int length);

    /**
     * Writes the specified {@link CharSequence} at the current
     * {@code writerIndex} and increases the {@code writerIndex} by the written
     * bytes. in this buffer.
     *
     * @param sequence to write
     * @param charset that should be used
     * @return the written number of bytes
     * @throws IndexOutOfBoundsException if {@code this.writableBytes} is not
     *         large enough to write the whole sequence
     */
    public abstract int writeCharSequence(CharSequence sequence,
            Charset charset);

    /**
     * Locates the first occurrence of the specified {@code value} in this
     * buffer. The search takes place from the specified {@code fromIndex}
     * (inclusive) to the specified {@code toIndex} (exclusive).
     * <p>
     * If {@code fromIndex} is greater than {@code toIndex}, the search is
     * performed in a reversed order.
     * <p>
     * This method does not modify {@code readerIndex} or {@code writerIndex} of
     * this buffer.
     *
     * @return the absolute index of the first occurrence if found. {@code -1}
     *         otherwise.
     */
    public abstract int indexOf(int fromIndex, int toIndex, byte value);

    /**
     * Locates the first occurrence of the specified {@code value} in this
     * buffer. The search takes place from the current {@code readerIndex}
     * (inclusive) to the current {@code writerIndex} (exclusive).
     * <p>
     * This method does not modify {@code readerIndex} or {@code writerIndex} of
     * this buffer.
     *
     * @return the number of bytes between the current {@code readerIndex} and
     *         the first occurrence if found. {@code -1} otherwise.
     */
    public abstract int bytesBefore(byte value);

    /**
     * Locates the first occurrence of the specified {@code value} in this
     * buffer. The search starts from the current {@code readerIndex}
     * (inclusive) and lasts for the specified {@code length}.
     * <p>
     * This method does not modify {@code readerIndex} or {@code writerIndex} of
     * this buffer.
     *
     * @return the number of bytes between the current {@code readerIndex} and
     *         the first occurrence if found. {@code -1} otherwise.
     *
     * @throws IndexOutOfBoundsException if {@code length} is greater than
     *         {@code this.readableBytes}
     */
    public abstract int bytesBefore(int length, byte value);

    /**
     * Locates the first occurrence of the specified {@code value} in this
     * buffer. The search starts from the specified {@code index} (inclusive)
     * and lasts for the specified {@code length}.
     * <p>
     * This method does not modify {@code readerIndex} or {@code writerIndex} of
     * this buffer.
     *
     * @return the number of bytes between the specified {@code index} and the
     *         first occurrence if found. {@code -1} otherwise.
     *
     * @throws IndexOutOfBoundsException if {@code index + length} is greater
     *         than {@code this.capacity}
     */
    public abstract int bytesBefore(int index, int length, byte value);

    /**
     * Iterates over the readable bytes of this buffer with the specified
     * {@code processor} in ascending order.
     *
     * @return {@code -1} if the processor iterated to or beyond the end of the
     *         readable bytes. The last-visited index If the
     *         {@link ByteProcessor#process(byte)} returned {@code false}.
     */
    public abstract int forEachByte(ByteProcessor processor);

    /**
     * Iterates over the specified area of this buffer with the specified
     * {@code processor} in ascending order. (i.e. {@code index},
     * {@code (index + 1)}, .. {@code (index + length - 1)})
     *
     * @return {@code -1} if the processor iterated to or beyond the end of the
     *         specified area. The last-visited index If the
     *         {@link ByteProcessor#process(byte)} returned {@code false}.
     */
    public abstract int forEachByte(int index, int length,
            ByteProcessor processor);

    /**
     * Iterates over the readable bytes of this buffer with the specified
     * {@code processor} in descending order.
     *
     * @return {@code -1} if the processor iterated to or beyond the beginning
     *         of the readable bytes. The last-visited index If the
     *         {@link ByteProcessor#process(byte)} returned {@code false}.
     */
    public abstract int forEachByteDesc(ByteProcessor processor);

    /**
     * Iterates over the specified area of this buffer with the specified
     * {@code processor} in descending order. (i.e.
     * {@code (index + length - 1)}, {@code (index + length - 2)}, ...
     * {@code index})
     *
     *
     * @return {@code -1} if the processor iterated to or beyond the beginning
     *         of the specified area. The last-visited index If the
     *         {@link ByteProcessor#process(byte)} returned {@code false}.
     */
    public abstract int forEachByteDesc(int index, int length,
            ByteProcessor processor);

    /**
     * Returns a copy of this buffer's readable bytes. Modifying the content of
     * the returned buffer or this buffer does not affect each other at all.
     * This method is identical to
     * {@code buf.copy(buf.readerIndex(), buf.readableBytes())}. This method
     * does not modify {@code readerIndex} or {@code writerIndex} of this
     * buffer.
     */
    public abstract ByteBuf copy();

    /**
     * Returns a copy of this buffer's sub-region. Modifying the content of the
     * returned buffer or this buffer does not affect each other at all. This
     * method does not modify {@code readerIndex} or {@code writerIndex} of this
     * buffer.
     */
    public abstract ByteBuf copy(int index, int length);

    /**
     * Returns a slice of this buffer's readable bytes. Modifying the content of
     * the returned buffer or this buffer affects each other's content while
     * they maintain separate indexes and marks. This method is identical to
     * {@code buf.slice(buf.readerIndex(), buf.readableBytes())}. This method
     * does not modify {@code readerIndex} or {@code writerIndex} of this
     * buffer.
     * <p>
     * Also be aware that this method will NOT call {@link #retain()} and so the
     * reference count will NOT be increased.
     */
    public abstract ByteBuf slice();

    /**
     * Returns a retained slice of this buffer's readable bytes. Modifying the
     * content of the returned buffer or this buffer affects each other's
     * content while they maintain separate indexes and marks. This method is
     * identical to {@code buf.slice(buf.readerIndex(), buf.readableBytes())}.
     * This method does not modify {@code readerIndex} or {@code writerIndex} of
     * this buffer.
     * <p>
     * Note that this method returns a {@linkplain #retain() retained} buffer
     * unlike {@link #slice()}. This method behaves similarly to
     * {@code slice().retain()} except that this method may return a buffer
     * implementation that produces less garbage.
     */
    public abstract ByteBuf retainedSlice();

    /**
     * Returns a slice of this buffer's sub-region. Modifying the content of the
     * returned buffer or this buffer affects each other's content while they
     * maintain separate indexes and marks. This method does not modify
     * {@code readerIndex} or {@code writerIndex} of this buffer.
     * <p>
     * Also be aware that this method will NOT call {@link #retain()} and so the
     * reference count will NOT be increased.
     */
    public abstract ByteBuf slice(int index, int length);

    /**
     * Returns a retained slice of this buffer's sub-region. Modifying the
     * content of the returned buffer or this buffer affects each other's
     * content while they maintain separate indexes and marks. This method does
     * not modify {@code readerIndex} or {@code writerIndex} of this buffer.
     * <p>
     * Note that this method returns a {@linkplain #retain() retained} buffer
     * unlike {@link #slice(int, int)}. This method behaves similarly to
     * {@code slice(...).retain()} except that this method may return a buffer
     * implementation that produces less garbage.
     */
    public abstract ByteBuf retainedSlice(int index, int length);

    /**
     * Returns a buffer which shares the whole region of this buffer. Modifying
     * the content of the returned buffer or this buffer affects each other's
     * content while they maintain separate indexes and marks. This method does
     * not modify {@code readerIndex} or {@code writerIndex} of this buffer.
     * <p>
     * The reader and writer marks will not be duplicated. Also be aware that
     * this method will NOT call {@link #retain()} and so the reference count
     * will NOT be increased.
     * @return A buffer whose readable content is equivalent to the buffer
     *         returned by {@link #slice()}. However this buffer will share the
     *         capacity of the underlying buffer, and therefore allows access to
     *         all of the underlying content if necessary.
     */
    public abstract ByteBuf duplicate();

    /**
     * Returns a retained buffer which shares the whole region of this buffer.
     * Modifying the content of the returned buffer or this buffer affects each
     * other's content while they maintain separate indexes and marks. This
     * method is identical to {@code buf.slice(0, buf.capacity())}. This method
     * does not modify {@code readerIndex} or {@code writerIndex} of this
     * buffer.
     * <p>
     * Note that this method returns a {@linkplain #retain() retained} buffer
     * unlike {@link #slice(int, int)}. This method behaves similarly to
     * {@code duplicate().retain()} except that this method may return a buffer
     * implementation that produces less garbage.
     */
    public abstract ByteBuf retainedDuplicate();

    /**
     * Returns the maximum number of NIO {@link ByteBuffer}s that consist this
     * buffer. Note that {@link #nioBuffers()} or {@link #nioBuffers(int, int)}
     * might return a less number of {@link ByteBuffer}s.
     *
     * @return {@code -1} if this buffer has no underlying {@link ByteBuffer}.
     *         the number of the underlying {@link ByteBuffer}s if this buffer
     *         has at least one underlying {@link ByteBuffer}. Note that this
     *         method does not return {@code 0} to avoid confusion.
     *
     * @see #nioBuffer()
     * @see #nioBuffer(int, int)
     * @see #nioBuffers()
     * @see #nioBuffers(int, int)
     */
    public abstract int nioBufferCount();

    /**
     * Exposes this buffer's readable bytes as an NIO {@link ByteBuffer}. The
     * returned buffer shares the content with this buffer, while changing the
     * position and limit of the returned NIO buffer does not affect the indexes
     * and marks of this buffer. This method is identical to
     * {@code buf.nioBuffer(buf.readerIndex(), buf.readableBytes())}. This
     * method does not modify {@code readerIndex} or {@code writerIndex} of this
     * buffer. Please note that the returned NIO buffer will not see the changes
     * of this buffer if this buffer is a dynamic buffer and it adjusted its
     * capacity.
     *
     * @throws UnsupportedOperationException if this buffer cannot create a
     *         {@link ByteBuffer} that shares the content with itself
     *
     * @see #nioBufferCount()
     * @see #nioBuffers()
     * @see #nioBuffers(int, int)
     */
    public abstract ByteBuffer nioBuffer();

    /**
     * Exposes this buffer's sub-region as an NIO {@link ByteBuffer}. The
     * returned buffer shares the content with this buffer, while changing the
     * position and limit of the returned NIO buffer does not affect the indexes
     * and marks of this buffer. This method does not modify {@code readerIndex}
     * or {@code writerIndex} of this buffer. Please note that the returned NIO
     * buffer will not see the changes of this buffer if this buffer is a
     * dynamic buffer and it adjusted its capacity.
     *
     * @throws UnsupportedOperationException if this buffer cannot create a
     *         {@link ByteBuffer} that shares the content with itself
     *
     * @see #nioBufferCount()
     * @see #nioBuffers()
     * @see #nioBuffers(int, int)
     */
    public abstract ByteBuffer nioBuffer(int index, int length);

    /**
     * Internal use only: Exposes the internal NIO buffer.
     */
    public abstract ByteBuffer internalNioBuffer(int index, int length);

    /**
     * Exposes this buffer's readable bytes as an NIO {@link ByteBuffer}'s. The
     * returned buffer shares the content with this buffer, while changing the
     * position and limit of the returned NIO buffer does not affect the indexes
     * and marks of this buffer. This method does not modify {@code readerIndex}
     * or {@code writerIndex} of this buffer. Please note that the returned NIO
     * buffer will not see the changes of this buffer if this buffer is a
     * dynamic buffer and it adjusted its capacity.
     *
     *
     * @throws UnsupportedOperationException if this buffer cannot create a
     *         {@link ByteBuffer} that shares the content with itself
     *
     * @see #nioBufferCount()
     * @see #nioBuffer()
     * @see #nioBuffer(int, int)
     */
    public abstract ByteBuffer[] nioBuffers();

    /**
     * Exposes this buffer's bytes as an NIO {@link ByteBuffer}'s for the
     * specified index and length The returned buffer shares the content with
     * this buffer, while changing the position and limit of the returned NIO
     * buffer does not affect the indexes and marks of this buffer. This method
     * does not modify {@code readerIndex} or {@code writerIndex} of this
     * buffer. Please note that the returned NIO buffer will not see the changes
     * of this buffer if this buffer is a dynamic buffer and it adjusted its
     * capacity.
     *
     * @throws UnsupportedOperationException if this buffer cannot create a
     *         {@link ByteBuffer} that shares the content with itself
     *
     * @see #nioBufferCount()
     * @see #nioBuffer()
     * @see #nioBuffer(int, int)
     */
    public abstract ByteBuffer[] nioBuffers(int index, int length);

    /**
     * Returns {@code true} if and only if this buffer has a backing byte array.
     * If this method returns true, you can safely call {@link #array()} and
     * {@link #arrayOffset()}.
     */
    public abstract boolean hasArray();

    /**
     * Returns the backing byte array of this buffer.
     *
     * @throws UnsupportedOperationException if there no accessible backing byte
     *         array
     */
    public abstract byte[] array();

    /**
     * Returns the offset of the first byte within the backing byte array of
     * this buffer.
     *
     * @throws UnsupportedOperationException if there no accessible backing byte
     *         array
     */
    public abstract int arrayOffset();

    /**
     * Returns {@code true} if and only if this buffer has a reference to the
     * low-level memory address that points to the backing data.
     */
    public abstract boolean hasMemoryAddress();

    /**
     * Returns the low-level memory address that point to the first byte of ths
     * backing data.
     *
     * @throws UnsupportedOperationException if this buffer does not support
     *         accessing the low-level memory address
     */
    public abstract long memoryAddress();

    /**
     * Decodes this buffer's readable bytes into a string with the specified
     * character set name. This method is identical to
     * {@code buf.toString(buf.readerIndex(), buf.readableBytes(), charsetName)}.
     * This method does not modify {@code readerIndex} or {@code writerIndex} of
     * this buffer.
     *
     * @throws UnsupportedCharsetException if the specified character set name
     *         is not supported by the current VM
     */
    public abstract String toString(Charset charset);

    /**
     * Decodes this buffer's sub-region into a string with the specified
     * character set. This method does not modify {@code readerIndex} or
     * {@code writerIndex} of this buffer.
     */
    public abstract String toString(int index, int length, Charset charset);

    /**
     * Returns a hash code which was calculated from the content of this buffer.
     * If there's a byte array which is {@linkplain #equals(Object) equal to}
     * this array, both arrays should return the same value.
     */
    @Override
    public abstract int hashCode();

    /**
     * Determines if the content of the specified buffer is identical to the
     * content of this array. 'Identical' here means:
     * <ul>
     * <li>the size of the contents of the two buffers are same and</li>
     * <li>every single byte of the content of the two buffers are same.</li>
     * </ul>
     * Please note that it does not compare {@link #readerIndex()} nor
     * {@link #writerIndex()}. This method also returns {@code false} for
     * {@code null} and an object which is not an instance of {@link ByteBuf}
     * type.
     */
    @Override
    public abstract boolean equals(Object obj);

    /**
     * Compares the content of the specified buffer to the content of this
     * buffer. Comparison is performed in the same manner with the string
     * comparison functions of various languages such as {@code strcmp},
     * {@code memcmp} and {@link String#compareTo(String)}.
     */
    @Override
    public abstract int compareTo(ByteBuf buffer);

    /**
     * Returns the string representation of this buffer. This method does not
     * necessarily return the whole content of the buffer but returns the values
     * of the key properties such as {@link #readerIndex()},
     * {@link #writerIndex()} and {@link #capacity()}.
     */
    @Override
    public abstract String toString();

    @Override
    public abstract ByteBuf retain(int increment);

    @Override
    public abstract ByteBuf retain();

    @Override
    public abstract ByteBuf touch();

    @Override
    public abstract ByteBuf touch(Object hint);
}
